Apparatus and method for separation of phases in a multiphase flow

ABSTRACT

A device is disclosed for the separation of liquid-liquid phase and/or a liquid-gas phase where one or more of the phases is suspended in water and has a bubble/drop/particle size in the sub micron and micron range, and/or fine particular organic or inorganic material is present in one or more of the phases. There is also disclosed a method and use for the device.

The present invention relates to a device for improved separation ofdifferent phases in multiphase streams, as it appears in theintroduction to the following claim 1.

More specifically, the invention relates to the separation of differentphases in a liquid-liquid stream, a liquid-gas stream, or said streamswhere also fine particular solid matter may be a part of the stream,where this is to be separated. More specifically, the invention relatesto an integrated device for gathering small oil drops and gas bubbles atthe outlet of a flotation cyclone, so that these may be released withthe liquid stream at the outlet of the clean water side of the flotationcyclone as large gas bubbles and large oil drops, which can very easilybe separated in another flotation cyclone connected in series in theliquid stream or in another suitable separation device.

Furthermore, the invention relates to the dosing of a sorption agent inthe flotation cyclone where the device is integrated.

The invention also relates to use of the device integrated in regularcyclone or flotation processes, or combination solutions of these, as itappears in the following independent and dependent claims.

The invention relates to the technology that concerns separatingmultiphase streams where the different streams have different netweight. It especially relates to separating oil, water and gas fromproduced water from the oil industry, but it also relates to separatingorganic and inorganic pollution in the same manner from general wastewater as well as drinking water, where the net weight of the desiredseparated material can be brought to a net weight lower than the mainliquid phase.

In hydrocarbons (oil/gas) that wells up from a formation to a productionplant, there is also water and solid particles. The water phase that isseparated early in the process plant is called produced water, and isreleased into the sea. It does however contain some oil in finelydivided form, and therefore represents a pollution of the sea. Producedwater should therefore be cleansed of this hydrocarbon before it isreleased.

The invention also relates to coalescing small drops of liquid of thesame phase in a multiphase liquid-liquid stream into large drops ofdifferent phases.

The invention also relates to the coalescence of micron and submicrongas bubbles in a liquid phase into larger gas bubbles, where these haveattached, as submicron and micro bubbles, to particulate and/orhydrophobic, and/or oleophilic pollution in the liquid phase. Micronrefers to sizes of μm, and submicron refers to sizes smaller than 1 μm.

The invention also relates to dosing of a very light sorption agent in aflotation cyclone in order to bring this in contact with pollution inthe liquid phase, so that the net weight of absorbed pollution in theliquid phase is significantly lighter, so that separation happenssignificantly easier in the flotation cyclone.

KNOWN METHODS

There are presently several variants of different hydro cyclones forseparation of components of different net weight.

The most common feature is that the multiphase liquid is processedtangentially into the circular chamber of the cyclone, where a centeredopen cylinder contributes to a high rotation speed on the multiphaseliquid. Centrifugal forces separate particles or liquid with the highestspecific density out towards the outer wall of the chamber, whilelighter liquid/gas is drawn to the cylinder at the center.

A vortex is formed under the cylinder where the phases of low net weightare gathered and pulled upwards in the cylinder, and the heavier phasefollows the outer wall and are processed out through the outlet at thebottom of the cyclone.

The light phase gathered in a vortex under the centered cylinder willrise upwards inside the cylinder and exit through the outlet as rejectif this phase is to be separated. If for instance particles or liquidwith net weight bigger than what is to be kept is contamination(pollution), the reject will stay at the bottom outlet of the cyclone,and a clean phase will rise in the centered cylinder in the inletchamber of the cyclone.

Separation suitability in multiphase streams as a consequence ofdifference in net weight, ΔSG (Delta Specific Gravity) under theinfluence of centrifugal forces is known to be approximatelylogarithmically proportional to the drop size of one of the phases to beseparated. The smaller the ΔSG, the larger the drop size needed forequally efficient separation. In the opposite case, with large ΔSG inthe different phases in a stream, smaller particles/drops can beseparated with the same centrifugal force.

For flotation submicron air/gas bubbles are therefore desired in orderto attach these to pollution in liquid, so that the pollution canachieve a low net weight.

It is known that by saturating air/gas in liquid (water) under pressure,oxygen/gas will expand with pressure reduction as oxygen/gas bubbles ofsubmicron size. It is further known that produced water in the oilindustry is processed from reservoirs under relatively high pressure.During further surface separation of oil/water/gas the pressure isreleased in the different separation steps prior to release into the seaor re-injection of water. It is know that gas bubbles then will bereleased with a size down to a few micron, and also gas bubbles smallerthan 1 micron. It is also known that some of the oil in the water thatis most difficult to separate is on the size order of 5 to below 1micron.

It is also known that gas may be added prior to a flotation cyclone, aswell as be recycled in a flotation cyclone for purification of oil fromproduced water.

It is known that success criteria for efficient separation in aflotation cyclone where gas bubbles are attached to pollution in orderto achieve net weight difference is dependent on bubble size. A largeramount of smaller bubbles have a better chance of connecting withpollution with subsequent attachment. Small bubbles are slower toseparate, and have a better chance at coming across pollution if theprocess provides enough time for this.

It is known that a gas bubble can bind an oil drop by adhesion with arelatively weak binding to the oil drop, or by the oil dropencapsulating the gas bubble, where this binding is formidably stronger.

It is known that adhesion is the most prominent of the well-knownflotation processes, and that gas bubbles in this case remove oil dropsof their own size or larger.

It is also well-known that the utilization of micro bubble flotation inknown flotation techniques means needing 3 times as long of a residencetime in the flotation tank in order for the bubbles attached topollution to have time to rise up to the skimmer/separation area. It isalso known that a 30-200 micron bubble size on air/gas requires a tankwith a surface area of 10 m² and a height of more than 2.6 mpr. 100 m³/tprocessed water with regular flotation techniques. The reason for thisis to prevent a short circuit stream of air/gas/pollution to be pulledout to the clean water side at the bottom of the flotation tank.

It is also known that there have been made so-called hybrid solutionswhere flotation, cyclone, and air/gas stripping principles have beencombined in one unit. These units have a typical flow speed of optimally40 seconds. Polluted water mixed with gas is brought tangentially into acylindrical tank. An inner cylinder covering ⅓ of the total height ofthe tank is typically placed in the center, corresponding to the vortexfinder cylinder in a standard cyclone, in order to increase the rotationspeed on the liquid. The speed is then interrupted under the cylinderand a vortex is created below the inner cylinder. Polluted material withgas flows up into the inner cylinder and is led away, and clean water isled out at the bottom of the cylinder tank.

This is described in patent applications U.S. Pat. No. 6,749,757 B2, andWO 2005/079946 A1, among others.

The oil and gas industries creates large emissions of produced waterthat requires cleansing. Emissions occurs when 30-80% water mixed withoil/gas is produced from the reservoirs. Water/oil/gas is separated atthe fields, and the water fraction which is not injected to thereservoir is released to the recipient after going through differentcleansing processes to lower the hydrocarbon content. Two water streamsis typical for one field. “A clean water stream” from pressurizedseparator typically has a volume of 10,000-100,000m³ water per day,depending on the size of the field. This first step of separation cantake the oil content down to 10-40 mg/l. The drop size of remaining oilfraction, which the present technology does not capture, is typicallythe portion below 5-10 micron.

In the second and third separator step of the oil/gas/water separation,1,000-5,000 m³ polluted water a day is typically generated on anoffshore field. This water, called “dirty water stream”, typically hasan oil content varying from 100-1,500 mg/l. This is usually cleanedusing flotation or coalescence filters and flotation. Known technologieswill not extract oil drops smaller than 5-10 micron, and emissionstherefore vary from 10-40 mg oil hydrocarbons/l.

Known technologies used for cleansing comprise the following:

-   -   Cyclones where oil is mechanically separated from water.    -   Combined feed of condensate under pressure for upgrading oil        drop size with subsequent separation in a cyclone.    -   Flotation cells where oil is floated out using gas flotation        (very light hydrocarbons, so-called fuel gas, or nitrogen as        flotation vehicle).    -   Combined flotation/cyclone/gas stripping where flotation takes        place in a vertical straight cylindrical tank with tangential        feed of liquid, and where a vortex breaking plate is mounted at        the bottom of the straight tank with a rounded bottom and top.    -   Coalescence of oil drops in a liquid stream using media or        plates inserted in the liquid stream.    -   Adsorption in prepared media filters.

All known processes may use flocculants or extraction agents to increasethe effect of the processes.

The limitation of the known methods is that they are not well-suited fortreatment of the large volumes of waste water generated, when it comesto removing oil drops smaller than 5-10 micron. This is for example oneof the main reasons why the average emission of oil in water produced bythe oil and gas industry today is approximately 16 mg/l in the NorthSea.

It is an aim of the present invention to bring forth a new and improveddevice, placed in a continuous process water stream in a multiphaseseparating flotation cyclone, which at the release of gas caused by thepressure drop at the inlet of the flotation cyclone, or by feeding gas,micro bubble gas or gas pressure saturated liquid, makes possible theseparation of oil/water/particles/gas with a drop/particle/bubble sizealso smaller than 5-10 micron, without such micro bubble gas feedrequiring longer residence time in the separation chamber for efficientseparation.

It is furthermore an aim of the present invention to bring forth a newand improved method for separating oil hydrocarbons from water, andespecially oil drops smaller than 5-10 micron, in a compact flotationcyclone utilizing a feed of, or the presence of, gas saturated liquidand micro bubble gas in the process water stream in front of the device.

It is furthermore an aim of the present invention to bring forth a newand improved method for separating oil from water in accordance with theaforementioned aims by also combining a use of the device where theprocess water is process with gas saturated water and micro bubble gasalone, or where additionally a flocculant and/or finely dispersedextraction agent is used and/or light and pulverized sorption agentdosed to increase the net weight difference of absorbable pollution andwater phase and thereby increase the degree of purification in theflotation cyclone.

It is an aim of the present invention to bring forth uses for separatingorganic and/or inorganic pollution in a continuous liquid stream.

The device, the methods and the uses according to the present inventionare characterized by the features evident from the characteristics ofthe following independent claims.

Further features of the present invention are indicated in the dependentclaims.

The present invention discloses a device which makes it possible toseparate oil hydrocarbons, including with a drop size of less than 5-10micron, from water, where there is gas in the liquid phase, or whereinfusion of micro bubble gas or gas pressure saturated water in acontinuous liquid stream with vigorous mixing can be added.

According to the present invention, there has been brought forth adevice which makes it possible to separate oil hydrocarbons, includingwith a drop size of less than 5-10 micron, without this resulting in thementioned small bubbles and oil drops requiring an increased residencetime in a cyclone or a flotation cyclone in order to be separated fromoil hydrocarbons.

Furthermore, a phase separating device has been brought forth which usesthe centrifugal force to increase the drop and bubble size of oil dropsand free gas, so that oil/gas, as the mixture leaves the traditionalseparation chamber in cyclones or flotation tanks, is coalesced andseparated as large drops/bubbles which can be separated in a newflotation cyclone connected in a series, without demands for thewell-known increased residence time for separation of microbubbles/drops by regular micro bubble flotation.

A device has been brought forth for increasing bubble, drop and gas sizein a multiphase process water stream, as well as improved separation ofthe phases for use as combined vortex breaker and former of a secondsuper powerful vortex in a cyclone or a flotation cyclone/flotation tankin order to particularly improve separation of submicrondrops/bubbles/particles in the process water.

A device has been brought forth for increasing bubble, drop and gas sizein a multiphase process water stream, as well as improved separation ofthe phases, to be used as immediately integrated second treatment stepin a cyclone/flotation tank to particularly improve separation ofsubmicron oil drops/bubbles/particles in the process water whichotherwise would be dragged through the separation step due to itsmicron/submicron state.

The present invention is characterized by placing the device in aflotation cyclone/flotation tank with tangential inlet, vortex finder,and outlet for reject stream and main stream, through which the mainstream is processed at an adequate speed to cause multiphase separationas a consequence of the gravitational pull on the phases of differentnet weight.

The invention is further characterized by processing the polluted liquidwith gas/pollution phases with different net weight through theflotation cyclone/flotation tank wherein the main portion of the phasescoalesce and some micro gas bubbles encapsulated by oil and coalescedoil/other pollution is led to the outlet in a traditional flotationcyclone or flotation, wherein the device placed in a conical outlet partof the main chamber in the flotation cyclone/flotation tank forms asuper strong second vortex which pulls in residual gas/drops, whichotherwise would follow the outlet stream as unpurified pollution.

The present invention is further characterized by that the device placedat the outlet of the flotation cyclone/flotation tank holds the superstrong vortex column uniformly to release large bubbles of gas/oil/lightmatter pulsating as the submicron bubbles/oil drops/light matter appearfrom the liquid stream is drawn into the saturated vortex column andthereby over saturates the uniform vortex column, whereupon thisreleases large bubbles and large coalesced/agglomerated fractions at theoutlet of the cone.

The present invention is further characterized by the option of usingthe device in combination with use of dosing of light extraction fluids,pulverized light sorption agent, or flocculants.

According to a preferred embodiment of the present invention, aseparation and coalescence inducing vortex breaker is placed inside aconical flotation cyclone/flotation tank, contributing to an additionalseparation step for submicron and low micron sized pollution. The vortexbreaker is a round plate centered in the cone, and it functions as anordinary vortex breaker, and stabilizes a traditional vortex column upagainst a vortex finder, while it simultaneously, outside the plate,releases liquid phase to the outlet. At the same time, the plate blocksthe second vortex formed below the breaker in the continuation of thecone, so that a saturated gas vortex column is formed which does notmigrate upwards in the cyclone past the breaker.

In a preferred embodiment of the present invention the round plate isplaced at an adequate distance from the outlet of the cone in order fora uniform vortex to form under the breaker, and after gas/oil saturationlies against the underside of the vortex breaker as a uniform gas/oilcone where water spins at great speed past the vortex cone.

In a preferred embodiment of the present invention, the water spin isaccelerated downwards in the cone, and the distance from the cone to thevortex breaker is such that the rotation speed/downward moving speed inthe cone prevents the second gas vortex from escaping past the vortexbreaker upwards in the tank.

In a preferred embodiment of the present invention, the distance fromthe vortex breaker to outlet of the cone is large enough for a constantgas/light liquid/light matter vortex to form under the vortex breaker,whereby this significantly accelerates the spin in water betweenunderside of the vortex breaker and the outlet of cone, so that hevortex as a consequence of a constant feed of light submicron bubbles ofgas/oil/light matter is saturated into a uniform gas cone with lightpollution/coalesced oil where the oil is mainly gathered at the bottomof the gas cone.

The present invention is further characterized by the possibility ofplacing the device in a closed flotation cyclone and with applied gaugepressure that in a pulsating manner purges reject and gas/air so thatthe saturated second vortex thereby releases, point by point, largecoalesced drops in an even stream by oversaturation as a consequence ofthe small pressure variations in the tank caused by the pulsatingpurging of reject.

The present invention is characterized by the option of using aflocculant and/or a light sorption agent dosed before, after or in theflotation cyclone, where the device according to the invention isintegrated.

The present invention is brought forth to be used in a cyclone, aflotation cyclone/tank where traditional separation of phases withdifferent net weight takes place over vortex breaker whereby theinvention is used as a second separation step, where separated matterfrom this step may be sent to a new separation, a cyclone, a flotationcyclone/tank for easy separation, or a separate integrated separationchamber.

The present invention may also be brought forth to be used in atraditional cylindrical flotation cyclone or tank, with a tangentialinlet where vortex breaker is placed over conic outlet so that spin asdescribed is induced, and so that a saturated gas column with thedescribed characteristics arises under the vortex breaker.

ADVANTAGES OF THE PRESENT INVENTION

The present invention distinguishes itself from existingprocesses/inventions by a vortex breaker in a flotation tank/flotationcyclone/cyclone with a conic outlet by placing a vortex breaker atsufficient distance from outlet producing a second vortex below thebreaker, where gas and/or multiphase liquid with different net weight,or other easily absorbed/extracted liquid in processed fluid phase formsa very powerful vortex uniform column of gas and/or light liquid phase,and/or sorption agent in a saturated vortex column. This column issaturated by coalescing submicron and low micron particulargas/oil/extraction agent/sorption agent, which normally would escape thetank in its original form.

The invention further distinguishes itself from known technologies bythe surprising discovery that the saturated conic vortex captured undervortex breaker periodically releases large gas bubbles and/or large oildrops/extraction agents/coagulated sorption agents, which in a followingseparation step are easily removed. This release happens fromoversaturation of gas in the second vortex and/or from the pulsatinggauge pressure in the flotation cyclone caused by pulsating purging ofreject pollution/gas.

The present invention distinguishes itself from existingprocesses/inventions by making possible the use of gas pressuresaturated water and micro bubble injection in process water streams toachieve improved separation of phases between different phases in liquidstream without this resulting in the residence time in separationequipment, and without dimensions of separation equipment having to beincreased as a consequence of submicron and micron bubbles needinglarger separation volume in the separation chamber.

The present invention distinguishes itself from existing inventions inthat far more finely dispersed water/gas/oil is post separated under thevortex breaker itself in a second vortex in a hydro cyclone/flotationcyclone or in a flotation tank into large coalesced drops/conglomerates,which is easily separated in an integrated separation chamber or in anew separation step.

The present invention distinguishes itself from existingprocesses/inventions in that gas naturally present in a pressurizedliquid stream by relief of pressure can be removed by separating gasbubbles from 10-5 micron and also under 1 micron in an extremegravitation applied by the second vortex under a vortex breaker in aconic outlet of a pressurized flotation cyclone, and that one from thisremoval also achieves significantly better removal of oil drops of thesame size.

The device according to the invention shall be explained in furtherdetail in the following description with reference to the correspondingfigure:

FIG. 1 shows the device placed in a closed flotation cyclone where

-   (1) Tangential inlet process water (alternatively mixed with    flocculant or hydrocolloid).-   (2) Injection of pressure gas saturated water/micro bubble gas/light    sorption matter.-   (3) Ejector for recycling gas/acceleration of spin in cyclone.-   (4) Gas pocket contained above vortex finder.-   (5) Reject oil/gas.-   (6) Valve reject for achieving gauge pressure in tank.-   (7) Traditional vortex finder.-   (8) Vortex breaker plate.-   (9) Conically shaped flotation cyclone tank.-   (10) Traditional first Vortex between the vortex finder and vortex    breaker.-   (11) Saturated Second vortex below vortex breaker.-   (12) Release [/emission] of large coalesced gas bubbles/oil drops    from the second vortex at the outlet of the flotation cyclone.

FIG. 1 shows a device in accordance with the present invention forcarrying out the method according to the invention.

The device comprises a treatment tank 9 (flotation cyclone tank) with aconically shaped bottom part 20 (like a cornet), and an uppercylindrically shaped tank part 22, as well as a upper top part 24 thatmay be dome shaped. This is just a shape example. In the bottom tip ofthe conical section 20 there is an outlet 26 where to a diversion pipe28 is mounted.

In the upper part and in the middle of tank 9 there is placed a commonvortex finder 7, which is a cylindrical body for influencing the streamsand the separation in tank 9 in a favorable manner.

In the upper half of tank 9 there is located a pipe 1 for additions,which is arranged tangentially, for tangential inlet of fluids to betreated. From the top of vortex finder 7 a pipe 5A is arranged, whichstretches upwards and out through the upper top part 24. This pipecontinues on as pipe 5B, wherein a valve is mounted for regulating theoutlet of oil/gas as will become apparent in the following.

In addition to outlet pipe 5, a second pipe 55 runs out of the top ofthe top part 24, and is coupled onto inlet pipe 1. This pipe 55 alsocomprises a valve 56 used for regulating streams from a gas pocket 4,which is located above the vortex finder 7 when the device is in use. Acoupled ejector 3 on pipe 55 is used for recycling gas from pocket 4.

More detailed for the process carried out by the present invention, FIG.1 shows how oil-containing water with gas or added gas/sorptionagent/flocculent/extractant is tangentially led into a closedtraditional flotation cyclone (1), where gas with the aid of an ejector(3) is recycled from the gas pocket (4), which is maintained above thevortex finder (7), contributing to increased spin and coalescence ofsmaller drops/bubbles, as well as stripping of oil/gas upwards in thetank. Gas pocket (4) above vortex finder (7) is maintained with a gaugepressure typically smaller than 1 bar by having the reject tubesubjected to counter pressure above the valve (6), whereby oil floatedto top liquid level by top vortex finder (7) blown out reject tube as aconsequence of the gauge pressure, and when the reject tube (5) slurpsgas the gauge pressure will drop a little, so that the oil level/liquidlevel again reaches above the inlet of the reject tube. The cycle isrepeated continuously, and in this manner separated oil is emptiedpulsating from the tank through the reject tube (5). The ejector (3)which recycles gas for stripping of oil drops/small gas bubbles mainlyin the upper part of the flotation cyclone, also functions as a releasetrigger for smaller gas bubbles/submicron bubbles by pressure beingreleased over this. ΔP over ejector (3) can typically be 0.5 bar, butalso a differential pressure up to 15 bar can be charged over theejector (3), and this releases a large fraction of very small gasbubbles that are not removed in the short residence time in theconically shaped flotation cyclone (9), where the typical residence timeof the liquid is between 25-60 seconds. Furthermore, the ejector (3)will with its construction function give extra speed to the water whichis brought tangentially into the flotation cyclone, so that the speed ofthe spin is increased around a traditional vortex finder (7). The speedof the spin is further increased downwards in the flotation cyclone as aconsequence of the conic shape of the tank (9). A vortex column of gasand light liquid/light particles are drawn towards the center of thecyclone tank (9) and stop at the Vortex breaker plate (8), and thereby avortex number 1 is formed between vortex breaker (8) and vortex finder(7). In this, oil, gas bubbles and light particles are led upwards inthe tank through vortex finder (7) to liquid surface against gas pocket(4) where separated components are led to reject through (5). Undervortex breaker plate (8) there is by the strong accelerated spin as aconsequence of the conic shape of the cyclone outlet and cyclone tank(9). This spin combined with a negative pressure forming under thevortex breaker plate (8) as a result of the kinetic energy of the liquidout the outlet of the cyclone tank, resulting in the very small anddifficult to separate oil drops and gas bubbles separating and forming auniform gas cone (11) with coalesced oil at the bottom under the vortexbreaker plate (8). By saturating this gas cone with coalesced oil (11)this releases large coalesced drops of oil/gas bubbles (12) out throughthe outlet of the flotation cyclone, and these are easily separated in anew separation step. Such release is also enhanced by the pulsatinggauge pressure in the tank as a result of the pulsating reject emissionthrough (5) over (6).

Test 1:

5000 l water was mixed with raw oil at 240 mg/l. Mixing was carried outin a shear mixing pump of type EDUR EB4u multiphase pump without mixingin gas. Measurements of the particle size of the oil drops showed that24 ppm of mixed raw oil had a particle size of less than 5 micron.

An attempt was made to remove oil using an injection of air bubbles infront of a compact cylindrical cyclone/flotation tank with an injectionof gas bubbles added in a standard injection mixer. The tank had acylindrical vortex finder and a vortex breaker plate placed 8 cm overcurved bottom with outlet at the center of the curve. Typical gas bubblesize was 50-150 micron. It was processed with process water polluted byoil with an intake rate of 1.6 m³/t.

Up to 45 ppm oil hydrocarbon was removed from purified water. 20 ppm ofthe measured residual pollution had a drop size of less than 10 micron.The test used a compact cyclone/flotation tank with residence time forprocess water stream of 40 seconds.

Test 2:

The tank from test 1 was then opened and a loose cone from the bottom ofthe vortex finder was placed against the outlet of the tank so that theactual treatment tank was given an appearance as shown in FIG. 1. Thereduced volume resulted in a decrease in residence time to 22 seconds,but the liquid received a powerfully accelerated spin. The same pollutedwater was processed, with the result of only 12 ppm oil coming through.The drop size of what came through was several hundred micron, and only1-2 ppm had a drop size of less than 10 micron. The tests were carriedout in Plexiglas tanks and with Plexiglas tubing. It was observed thatthe water was free of small gas bubbles after outlet as the secondvortex below the vortex breaker plate had stabilized. It was furthermoreobserved that the uniform vortex cone under the vortex breaker platereleased large gas/oil drops which appeared like pearls on a string inthe outlet tube. The test clearly showed that the small drops whichpassed without being purified in test one were now coalesced in thevortex column and were released as large drops, and that the same thinghappened with the smallest drops.

Test 3:

The configuration from test 2 was used, only this time an additionaltank was connected to the first tank in a series. This was done in orderto be able to separate the large coalesced drops which were detected atthe outlet of tank 1 in test 2.

The result was that now, after tank 2, there was only 1-2 ppm oil in thedischarge water. All oil in the discharge had a particle size of lessthan 1 micron. The test showed that the device used in a flotationcyclone coalesces oil drops smaller than 1 micron so that these can beseparated in a purification step 2. Such small oil drops cannot beseparated using known technology.

Test 4:

The configuration from test 3 was used, with the difference that thistime a heat activated peat moss powder was dosed between tank 1 and 2 asa sorption agent. This was attempted dosed both wet as slurry, and dryas powder. In both cases 3 ppm heat activated peat moss was dosed, whichwas completely removed in flotation cyclone 2. In both cases the oilcontent in the discharge water was below the limit for detection for theanalysis at 0.3 ppm.

1. A separation device for the separation of fluid phases in amultiphase stream, where part of one or more of the phases is suspendedin water and has a drop size in the submicron and micron size rangewhere fine particular organic or inorganic material is present in one ormore of the phases, or part of one or more of the phases is suspended inwater and has a drop size in the submicron and micron range and fineparticular organic or inorganic material is present in one or more ofthe phases, wherein the device is located in a conical outlet in aseparation tank with a tangential inlet for process water, and thedevice comprises a circular plate shaped vortex breaker having a topsurface arranged to break a vortex against a vortex finder andsimultaneously, under the vortex breaker in the conical outlet, thedevice is arranged to form a second uniform vortex column comprising oneor more of bubbles, drops, extraction agents of low micron and submicronsize and particles of net weight lower than the fluid phases, whereinreject from floated pollution and gas in the first vortex is bled off ina pipe where the bleed off is generated by gauge pressure in theseparation device, pulsating from bleed off of reject and gas from thefirst vortex gives a pulsating release of large drops of coalescedmaterial selected from oil, gas, particulates and mixtures thereof, fromsaid second uniform vortex column under the vortex breaker.
 2. Aseparation device in accordance with claim 1, wherein the device isplaced in a conical outlet of an apparatus selected from the groupconsisting of a pressurized hydro cyclone, a flotation cyclone. aflotation tank with a tangential inlet for process water, and that thesecond uniform vortex column escapes forces applied by a spin in themultiphase stream above the vortex breaker and thereby follows themultiphase stream to an accelerated spin below the breaker so that astatic vortex column is formed under the vortex breaker, which aftersaturation as a result of steady infusion of one or more of low micronand submicron gas bubbles, oil drops, extraction agents and particles ornet weight lower than the fluid phases, releases one or more of largecoalesced bubbles, drops and agglomerated particles out in an outflow.3. A separation device in accordance with claim 1 for one or both ofcoalescence and pre-separation and increase of the net weight differenceof the different phases, wherein light sorption material is injectedinto the multiphase stream during, before or after the multiphase streamreaches a ring-shaped area located between the saturated gas in thesecond vortex and an inner wall of the conical outlet.
 4. A separationdevice in accordance with claim 2 for one or both of coalescence andpre-separation and increase of the net weight difference of thedifferent phases, wherein light sorption material is injected into themultiphase stream during, before or after the multiphase stream reachesring-shaped area located between the saturated gas in the second vortexand an inner wall of the conical outlet.
 5. A separation device inaccordance with claim 1, wherein several tanks are connected in parallelor in series.
 6. A separation device in accordance with claim 2, whereinseveral tanks are connected in parallel or in series.
 7. A separationdevice in accordance with claim 3, wherein several tanks are connectedin parallel or in series.
 8. A separation device in accordance withclaim 4, wherein several tanks are connected in parallel or in series.9. A separation device in accordance with claim 1, wherein an additionalseparation device for separating large drops of coalesced materialselected from oil, gas, particulates and mixtures thereof, is locatedafter an outlet from the second uniform vortex column.
 10. A separationdevice in accordance with claim 2, wherein an additional separationdevice for separating large drops of coalesced material selected fromoil, gas, particulates and mixtures thereof, is located after an outletfrom the second uniform vortex column.
 11. A separation device inaccordance with claim 3, wherein an additional separation device forseparating large drops of coalesced material selected from oil, gas,particulates and mixtures thereof, is located after an outlet from thesecond uniform vortex column.
 12. A separation device in accordance withclaim 4, wherein an additional separation device for separating largedrops of coalesced material selected from oil, gas, particulates andmixtures thereof, is located after an outlet from the second uniformvortex column.
 13. A separation device in accordance with claim 5,wherein an additional separation device for separating large drops ofcoalesced material selected from oil, gas, particulates and mixturesthereof, is located after an outlet from the second uniform vortexcolumn.
 14. A separation device in accordance with claim 6, wherein anadditional separation device for separating large drops of coalescedmaterial selected from oil, gas, particulates and mixtures thereof, islocated after an outlet from the second uniform vortex column.
 15. Aseparation device in accordance with claim 7, wherein an additionalseparation device for separating large drops of coalesced materialselected from oil, gas, particulates and mixtures thereof, is locatedafter an outlet from the second uniform vortex column.
 16. A separationdevice in accordance with claim 8, wherein an additional separationdevice for separating large drops of coalesced material selected fromoil, gas, particulates and mixtures thereof, is located after an outletfrom the second uniform vortex column.
 17. Method for phase separationand coalescence of one or more of oil hydrocarbons, gas bubbles, lightparticles and mixtures thereof, in a water stream, in, after, or beforeone or more of a cyclone tank and a flotation tank, comprising the stepsof generating, in a continuous stream in an outlet of a separationdevice, a vortex under a vortex breaker which cannot escape against thedirection of a liquid stream passing the vortex breaker, so thatsaturation of the vortex arises from one or more of gas and pollutiondragged into the vortex, wherein under the vortex breaker in a conicaloutlet there is brought forth a saturated second vortex column wherein apulsating pressure in the separation device causes a pulsating output oflarge drops of coalesced matter selected from oil, gas, particulates andmixtures thereof, from the second saturated vortex column under thevortex breaker.
 18. Method in accordance with claim 17, wherein phaseseparation and coalescence of one or more of oil hydrocarbons, gasbubbles and light particles in the water stream, in, after or before oneor more of a cyclone and flotation tank, is at least partially caused byinjection of a light sorption agent during, before or after the waterstream is located in a ring-shaped space between a saturated gas in thesecond saturated vortex column and an inner wall of the conical outlet.19. Method in accordance with claim 17, wherein for phase separation andcoalescence of one or more of oil hydrocarbons, gas bubbles and lightparticles in the water stream, in, after or before one or more of acyclone and flotation tank, there is after the separation deviceaccording to claim 1, at least two additional devices selected fromdevices according to claim 1 or other separation devices are connectedin series.
 20. Method in accordance with claim 18, wherein for phaseseparation and coalescence of one or more of oil hydrocarbons, gasbubbles and light particles in the water stream, in, after or before oneor more of a cyclone and flotation tank, there is after the separationdevice according to claim 1, at least two additional devices selectedfrom devices according to claim 1 or other separation devices areconnected in series.